Zinc Acetate Solution Research Articles

Tourmaline@ZnO Core–Shell Structural Composites: Fabrication, Characterization, and Optical Properties

Based on natural tourmaline particles as the inner core and zinc acetate solution as the Zn source, ZnO shell layers have been fabricated by the facile synthesis routine of chemical bathing deposition under different reaction temperatures. The structural and crystalline characterization of the core–shell composites are determined experimentally by Raman spectra and x-ray diffraction. The morphological and componential investigations are achieved by scanning electron microscopy, high-resolution transmission electron microscopy and energy dispersive spectrometer. The absorptive and luminescent properties are explored by ultraviolet–visible absorption spectroscopy and photoluminescence spectroscopic measurements. The photocatalytic performances are evidenced under Xenon lamp irradiation utilizing methyl orange dye as the model compound. The results indicate that the catalysis efficiencies of the hybrid tourmaline@ZnO products are relatively superior in lower temperature cases, while the contributions originating from the tourmaline core to the crystal growth and catalytic activity of ZnO are further elucidated.

Synthesis of zinc oxide microrod arrays and their performance as piezo-generators

ABSTRACTZinc oxide microrods were synthesized by aqueous chemical growth using zinc nitrate and zinc acetate solutions without seed layer. Rod length of around 10 µm was obtained after 5 hr at 95°C. Solution replenishment led to a better alignment normal to the substrate; however, only zinc acetate solution resulted in bigger rods, reaching about 12 µm in length and 5 µm in diameter. X-ray diffraction revealed a pure hexagonal wurtzite structure with high crystallographic texture. Raman spectroscopy showed no evidence of lattice stress. The ZnO microrod arrays were used to fabricate piezoelectric generators, and the largest output was obtained from the generator with the higher density of rods. The use of a piezoelectric polymer in the generators led to an improved performance of at least 200% compared to reports that used a dielectric polymer.

Rapid In Situ Encapsulation of Laccase into Metal‐Organic Framework Support (ZIF‐8) under Biocompatible Conditions

AbstractIn situ immobilization of laccase into metal‐organic framework (laccase‐MOF) was performed by assisting one‐pot synthesis strategy. A novel method to synthesize octahedral laccase‐MOF composite with enhanced thermostability is reported. The present work deals with entrapment of laccase into zeolitic imidazolate framework (ZIF‐8) by simply mixing solution of zinc acetate, 2‐methylimidazole, and laccase at room temperature (28 ± 2 °C). Fourier transform‐infrared spectroscopy (FT‐IR), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), and Confocal scanning microscopy were employed to characterize laccase‐MOF composite. The thermostability of prepared composite was assessed concerning half‐life at varying temperatures which conferred 3.6‐fold enhancement over free enzyme. Also, kinetic studies of immobilized laccase showed a slightly higher Km and lower Vmax values along with the enhancement of thermodynamic parameters after non‐covalent interaction. Moreover, the immobilized laccase‐MOF maintained up to 48% of residual activity for seven subsequent cycles in batch mode, whereas the storage stability studies exhibited up to 83% up to 21 days of storage. Finally, FT‐IR data tool was employed to investigate the effect of encapsulation on fractions of secondary structure of protein.

Oxidized guar gum–ZnO hybrid nanostructures: synthesis, characterization and antibacterial activity

In the present study, guar gum (GG) and oxidized guar gum (OGG) have been used for modulating the antibacterial activity of ZnO. Oxidized guar gum–zinc oxide (OGG–ZnO) or guar gum–zinc oxide (GG–ZnO) nanostructures were synthesized by adding aqueous ammonia to zinc acetate solution in the presence of OGG or GG, respectively. OGG could significantly enhance the antibacterial activity of ZnO for a range of Gram-negative and Gram-positive bacterial strains and this enhancement was most pronounced for Bacillus subtilis and Salmonella typhi. At the same time, GG–ZnO nanostructures were found to be less bioactive than the pure ZnO for the same strains. TEM analysis revealed that optimum OGG–ZnO nanostructure (Z4) is of ~ 200 nm size, oblong in shape, and has slightly clustered texture, while XRD confirmed its crystalline structure with hexagonal phase. The extra surface oxygen species (thus oxygen deficiency) has been assigned for better antibacterial behavior of OGG–ZnO. The study may be extended for other polysaccharide/derivatives to obtain ZnO nanostructures with enhanced antibacterial properties.

Effect of annealing atmosphere on structural and optical properties of CZTS thin films prepared by spin-coating

Copper zinc tin sulfide (CZTS) thin films were deposited by spin coating procedure of a sol-gel prepared from the solution of copper (II)chloride, zinc acetate, tin (II) chloride and thiourea in 2-methoxyehtanol followed by annealing under two different atmospheres viz. N2 gas and Sulphur (S) powder at 530 °C for 5 minutes. The effect of different annealing atmosphere on the structural and optical properties of the CZTS thin films were investigated. The X-ray diffraction study showed higher intensity peaks for films annealed under N2 gas ambient. SEM study revealed that the surfaces of the films in both cases are non-uniform. Films annealed in N2 gas atmosphere showed better absorption coefficient (exceeding 104 cm-1 in the visible region) than the sulphurized ones. The optical band gap (Eg) of the films were found to be in the range of 1.46 - 1.53 eV.Bangladesh J. Sci. Ind. Res.53(1), 13-20, 2018

Reversible CO2 capture by ZnO slurry leading to formation of fine ZnO particles

ZnO powders were synthesized by heating precursors, prepared by the addition of ethylene diamine tetraacetate to an aqueous solution of zinc acetate, at 500 °C in air. A ZnO slurry was prepared by adding distilled water to the synthesized ZnO powder. X-ray diffraction studies confirmed that the ZnO slurry adsorbed CO2 at 25 °C under a CO2 gas flow to produce Zn5(CO3)2(OH)6. The CO2 adsorption ratio of the ZnO slurry was influenced by the amount of added water. When the weight ratio of water/ZnO was 1, the ZnO slurry had the largest CO2 adsorption ratio. Scanning electron microscopy and thermal gravimetry showed that the plate-like Zn5(CO3)2(OH)6 particles thermally decomposed at 300 °C in air leading to a single-phase ZnO powder consisting of nanoparticles with approximately 20 nm in diameter. The specific surface area of the reformed ZnO powder increased to approximately 82 m2/g through the thermal decomposition of Zn5(CO3)2(OH)6. The ZnO slurry was capable of adsorbing CO2 under a CO2 flow at 25 °C and desorbing CO2 under an air flow at 300 °C. The CO2 adsorption ratio of the ZnO slurry reached 80%–90% at 25 °C even after the fifth CO2 adsorption and desorption cycle.

Hydrothermally Synthesized Zinc Sulphide Microspheres for Solar Light-Driven Photocatalytic Properties

In this work, we reported the synthesis of zinc sulphide microspheres using the hydrothermal method. ZnS microspheres were synthesized using water, zinc acetate, thiourea and ammonia solution at 150°C for 6 h, 12 h, and 24 h. The as-synthesized ZnS powders were characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet–visible (UV–Vis) spectroscopy. XRD indicates the cubic (major phase) as well as hexagonal (minor phase) crystalline phase with enhanced crystallinity increased gradually with more reaction time. UV–Vis spectra show the absorption peaks in the UV–Vis region for all the samples. The Tauc’s plot was used to calculate the band gap energy of ZnS samples, which are found to be 3.39 eV, 3.4 eV, and 3.42 eV for the samples synthesized at reaction times of 6 h, 12 h, and 24 h, respectively. FESEM images confirm the formation of microspheres as aggregates of spherical nanoparticles. The as-synthesized ZnS microspheres have been explored for solar light-induced photo-catalytic dye degradation of methylene blue (MB), and the results confirm that such microspheres exhibit effectual photocatalytic properties. Zinc sulphide microspheres have been synthesized hydrothermally at different reaction times (6 h, 12 h, and 24 h). The as-synthesized ZnS microspheres were successfully employed as photocatalyst for MB dye degradation. Due to high crystallinity, ZnS microspheres synthesized for 24 h show more efficient degradation potential than others.

ANTIDERMATOPHYTIC ACTIVITY OF GREEN SYNTHESISED ZINC OXIDE NANOPARTICLES USING Cassia alata LEAVES

The green techniques are plying a major role in the synthesis of nanoparticles and in this present study we used the herbal plant Cassia alata for the green synthesis of zinc oxide nanoparticles. This reducing agent generates zinc oxide nanoparticles (ZnO NPs) from zinc acetate solution within 15 minutes. The synthesized ZnO NPs was characterized by UV-vis spectrophotometer shows surface Plasmon resonance band at 335 nm. Scanning electron microscope (SEM) image showed the size of the crystalline nanoparticles ranging from 30- 50 nm. Energy dispersive X-ray analysis (EDAX) confirms the presence of elemental Zn and O in the synthesized nanoparticles. FTIR revealed that presence of functional molecules like carboxylic acids, amine ant nitro groups associated with synthesized oxide nanoparticles. Atomic force microscope (AFM) shows spherical shape of nanoparticles as well as aggregation also observed. Thus green synthesized nanoparticles were tested for their antidermatophytic potential against Trichophyton mentagrophyte, Trichophyton rubrum, Epidermophyton floccosum, Microsporum audouinii, and Microsporum canis and recorded percentage of inhibition, MIC and MFC values.

Size control mechanism of ZnO nanoparticles obtained in microwave solvothermal synthesis

The aim of the paper is to explain the mechanism of zinc oxide (ZnO) nanoparticle (NP) size control, which enables the size control of ZnO NPs obtained in microwave solvothermal synthesis (MSS) within the size range between circa 20 and 120 nm through the control of water content in the solution of zinc acetate in ethylene glycol. Heavy water was used in the tests. The mechanism of ZnO NPs size control was explained, discussed and experimentally verified. The discovery and investigation of this mechanism was possible by tracking the fate of water molecules during the whole synthesis process. All the synthesis products were identified. It was indicated that the MSS of ZnO NPs proceeded through the formation and conversion of intermediates such as Zn5(OH)8(CH3COO)2 · xH2O. Esters and H2O were the by-products of the MSS reaction of ZnO NPs. We justified that the esterification reaction is the decisive stage that is a prerequisite of the formation of ZnO NPs. The following parameters of the obtained ZnO NPs and of the intermediate were determined: pycnometric density, specific surface area, phase purity, average particles size, particles size distribution and chemical composition. The ZnO NPs morphology and structure were determined using scanning electron microscopy.

Template‐free Fabrication of ZnS/TiO2 Photocatalyst with Macrochannels

Constructing a porous structure in photocatalysts is an effective strategy for improving the photocatalytic activity because of its enhanced molecule transfer capability and light capturing efficiency. In this work, a hierarchical macro‐/mesoporous ZnS/TiO2 composite with macrochannels was successfully synthesized without using templates by the simple dropwise addition of an ethanol solution of tetrabutyl titanate and zinc acetate into a sodium sulfide aqueous solution, which was then calcined at 450°C. Compared with pure TiO2, the ordered porous ZnS/TiO2 composite exhibited an enhanced photocatalytic activity on methylene blue removal under UV‐light irradiation. The results indicate that the macro‐/mesoporous structure, the large specific surface area, and the heterostructure combination between ZnS and TiO2 play a synergistic effect on the enhanced photocatalytic activity via improving the light absorption and the diffusion of organic molecules, providing more reactive sites for the photocatalytic reaction and improving the separation of photogenerated electron–hole pairs, respectively. Radical trapping experiments demonstrated that holes (h+) and superoxide anion radicals (O2−) play an important role in the photocatalytic oxidation process.

Decomposition of solution droplets under the influence of thermal convection over a heated horizontal plate

Experimental approaches using an open-plate reactor were proposed to investigate the thermal decomposition and deposition processes of solution droplets sprayed over a heated horizontal plate. The temperature-dependent flow condition of the carrier gas may influence the properties of incoming sprayed aerosols. Zinc oxide (ZnO) particle layers were synthesized by spraying zinc acetate solution to the plate with deposition angle of 45°. The prepared particle layers and a numerical simulation verified the presence of thermally generated convection and fluid instability. Correlation between the size and morphology of deposited aerosols and the dynamical condition due to temperature distribution above the plate has been analyzed. A short distance (2 cm) between the nozzle and the plate will prepare finer (nanometer-scaled) ZnO particle layers. ZnO with higher crystallinity can be prepared using one-step route (directly spraying at 450 °C) compared with those of two-step heating procedures (150 °C – spraying then 450 °C – re-heating in 1 h), which consume higher energy.

Inverted polymer solar cells with brush-painted ZnO electron transport layer

Air-stable inverted polymer solar cells (IPSCs) were demonstrated by incorporating ZnO electron transport layer (ETL) fabricated with low-cost and simple brush-painting. IPSC with brush-painted ZnO using commonly used 0.75M zinc acetate solution in 95% 2-methoxyethanol and 5% ethanolamine showed poor efficiency and reproducibility. By optimizing precursor solution and substrate temperature, thieno[3,4-b]thiophene/benzodithiophene (PTB7): [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) based IPSC with high power conversion efficiency (PCE) of 7.63% and desirable device stability was achieved. This indicates that because optimized process conditions are not necessarily transferrable between different techniques, it is worthy of investigation and discussion.

Fabrication of Ag@AgCl/ZnO submicron wire film catalyst on glass substrate with excellent visible light photocatalytic activity and reusability

Conventional ZnO powder catalysts possess excellent stability and photocatalytic activity, but have great difficulties for separation and regeneration after the reaction and require ultraviolet irradiation (less than 5% of solar energy), thus restricting practical applications. In this paper, unique short submicron wire-like ZnO films were successfully prepared on silicate glass substrates by calcination of spin-coated zinc acetate solution in the presence of ethanolamine (EA). A typical synthesis yields ZnO submicron wires with ca. 50–120 nm in diameter, 15–30 μm in length and 0.5–1.5 μm in height. Ag@AgCl particles were deposited on short ZnO submicron wire films by a simple impregnating-precipitation-photoreduction method. The as-prepared Ag@AgCl/ZnO film exhibited efficient photocatalytic performance under visible light irradiation and excellent self-cleaning capability under solar light. This film photocatalysts were easy to separate from the reaction, and the tests showed that the films were reusable for four times without significantly loosing efficiency. Additionally, gas chromatography–mass spectroscopy (GC–MS) was applied to investigate the degraded chemical species resulted from the photo-catalytic degradation of methylene blue (MB) and methyl orange (MO) dyes under Ag@AgCl/ZnO. A possible photocatalytic mechanism was proposed based on the photoelectrochemical measurements and radical trapping experiments.

Mechanical characterization of stacked thin films: The cases of aluminum zinc oxide and indium zinc oxide grown by solution and combustion synthesis

Mechanical properties of multilayer films of aluminum zinc oxide (AZO) and indium zinc oxide (IZO) prepared from precursors obtained by solution and combustion synthesis have been characterized through nanoindentation. The AZO films have been prepared from solution of zinc acetate dehydrate doped by aluminum chloride, while IZO films have been obtained by mixing indium nitrate hydrate and zinc nitrate hexahydrate in various proportions. The preparation of solutions requires use of 2-methoxyethanol as solvent and of urea as fuel. Each film of the multilayer stack has been spin-coated, on glass substrate. Films of AZO and of IZO have been heated according to different recipes. X-rays diffraction measurement showed that AZO films were c-axis oriented with hexagonal wurtzite structure, while IZO films showed cubic bixbyite structure. We observe that, for crystalline films, the mechanical behavior follows normal Hall-Petch relation, while in case of amorphous films the hardness came from dopant atoms with higher atomic radii that stresses the lattice due to the size difference.

Encapsulation of lipase within metal-organic framework (MOF) with enhanced activity intensified under ultrasound.

The enzyme under lower-intensity ultrasonic irradiation leads to favorable conformational changes, thereby enhancing its activity. In this study, lipase activity was augmented upto 1.6-folds after ultrasonic treatment at 22kHz and 11.38Wcm-2 for 25min. This highly activated lipase was encapsulated within zeolite imidazolate framework-8 (ZIF-8) as a metal-organic framework (MOF) material via facile one-step biomineralization method by simply mixing aqueous solution of 2-methylimidazole (13.3mmol) and zinc acetate (1.33mmol) along with sonicated lipase within 10min at room temperature (28±2°C). The prepared lipase-MOF was characterized by using FT-IR, FT-Raman, XRD, BET, confocal scanning laser microscopy, TGA and SEM. Further, the thermal stability of lipase embedded MOF was evaluated in the range of 55-75°C on the basis of half-life which showed 3.2 folds increment as against free lipase. In Michaelis-Menten kinetics studies, sonicated lipase entrapped MOF showed nearly same Km and Vmax values as that of sonicated free lipase. Moreover, the immobilized lipase exhibited up to 54% of residual activity after seven successive cycles of reuse, whereas it retained 90% of residual activity till twenty-five days of storage. Finally, the conformational changes occurred in lipase after sonication treatment and encapsulation within MOF were analyzed by using FT-IR data analysis tools and fluorescent spectroscopy.

Influence of phase composition and textural features of ZnMoO4–MoO3 systems on the photocatalytic degradation of methyl red

The studied samples ZnMoO4–MoO3, have been prepared by immersing an amount of molybdenum oxide in zinc acetate solution according to the appropriate molar ratio x = ZnO/MoO3 = 0, 0.2, 0.4, 0.6, 0.8 and 1. These samples were then heated at temperature of 500°C for 3 hours. Prepared samples were characterized using different techniques such as: X-ray diffraction, Fourier spectroscopy, Raman spectroscopy, differential thermal analysis and nitrogen adsorption-desorption measurements. The Photocatalytic activity was studied via degradation of methyl red in aqueous solution when subjected to UV radiation. The results of this work revealed some variations, by increasing ZnO quantity, in phase composition and textural characteristics of ZnMoO4–MoO3 samples. It was found that these changes affect the photocatalytic activity by enhancing the degradation rate of Methyl red during the UV irradiation process.

Tuning optical, electrical and magnetic properties of fiber structured ZnO film by deposition temperature and precursor concentration

Highly transparent ZnO films were deposited on glass substrates using zinc acetate solution through cost effective spray pyrolysis method. A comprehensive study was carried out to understand the effects of deposition temperature and precursor concentrations on structure, surface morphology, optical, electrical and magnetic properties of the deposited films. All deposited films were polycrystalline in nature with hexagonal wurtzite structure. The films were preferentially oriented along (1 0 1) plane up to 723K beyond which orientation changed to (0 0 2) plane. Irrespective of precursor concentration used, the films deposited at 673K and 723K showed fibrous structure. The films deposited at higher temperature led to enhanced transmittance and optical energy band gap. With higher precursor concentrations the transmittance decreased while the band gap increased. Photoluminescence studies revealed the presence of various defects leading to emission in the visible region apart from band to band transition near UV region. Lowest electrical resistivity was obtained for films deposited at 723K which is of the order 102Ωcm. At room temperature, all deposited films were diamagnetic while they were paramagnetic at 5K.

Fabrication of zinc oxide-embedded kapok (Ceiba pentandra) paper

Zinc oxide-embedded kapok (Ceiba pentandra) papers with antimicrobial property were fabricated. Fabrication of papers from kapok fibers was done using chloroform and sodium chlorite treatments. Meanwhile, embedding of zinc oxide particles on the fabricated kapok papers was done using an in situ method. The said method involved soaking the paper in zinc acetate and sodium hydroxide solutions. The method also involved heat treatment of the sample to fasten the formation of zinc oxide particles. X-ray diffraction (XRD) measurement shows the presence of synthesized ZnO particles on the cellulose fibers while scanning electron microscopy (SEM) revealed the flake-like morphology of the embedded ZnO particles. Agar diffusion test shows that the samples have higher antimicrobial effect against Staphylococcus aureus than Escherichia coli.

Structural, optical and ammonia sensing properties of nanostructured ZnO thin films deposited by spray pyrolysis technique

In the present work, nanostructured ZnO thin films have been synthesized using spray pyrolysis technique by using the precursor solution of zinc acetate at 0.05, 0.1 and 0.15 M Concentration. X-ray diffraction patterns confirmed the polycrystalline nature of the films with hexagonal structure. The field-emission scanning electron micrograph of all the samples revealed the spherical grain value and the morphology undergoes a change according to molarity concentration. The ammonia (NH3) sensing properties of the films were performed at room temperature and the sensing responses of the samples towards NH3 concentrations were recorded.

Synthesis of ZnO-CuO/MCM-48 photocatalyst for the degradation of organic pollutions.

The photocatalytic properties of ZnO-CuO catalysts supported on siliceous MCM-48 (Mobil Composition of Matter No. 48) for the degradation of organic pollutions such as methylene blue and salicylic acid under UV light irradiation were investigated. These catalysts were prepared by impregnation of MCM-48 with a mixed aqueous solution of copper acetate and zinc acetate. X-ray diffraction, N2-physisorption, high resolution transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and photoluminescence were used to characterize these samples. Results from characterizations showed that the addition of ZnO to CuO/MCM-48 could markedly improve the photocatalytic degradation properties. The enhanced photocatalytic behaviors of ZnO-CuO/MCM-48 may be due to the formation of p-n heterojunctions between ZnO and CuO, resulting in the effective separation of photogenerated electron-hole pairs. Moreover, the photocatalysts were easily recovered and reused for five cycles without considerable loss of activity.